Unitil combines electric and gas AMI project

When Unitil Corp. began searching for an advanced metering infrastructure (AMI) system for their electric and gas accounts, they knew what they wanted: a single system that could reliably function in the challenging topography of their New England service territories.

In addition to a multi-utility system capable of reading electric and gas meters, Unitil preferred a fixed network that would function well in the area’s hilly topography and link between numerous communities. Past experience with RF convinced staff that 100 percent coverage would be difficult to achieve without installing and maintaining an extensive infrastructure.

“We leaned toward a power line carrier-based system for a number of reasons,” said Mike Deschambeault, Unitil’s AMI project manager. “We wanted the range and the communication functions the system provides. It’s a new communication system for us, but it has the look and feel of something we’re used to. The one thing we know is our distribution system.”

Finally, Unitil wanted a scalable technology capable of providing a level of functionality for value-added benefits, such as on demand reads, voltage monitoring, time-based rate structures, outage management and remote service disconnect.

TS2 Multi-utility

The TS2 Multi-utility system best fit all of these criteria. It is a power line carrier-based AMI system with integrated short-hop RF technology that communicates with electric, water and gas meters with a single network.

At the core of the system is a multi-utility module equipped with an antenna that enables it to communicate by way of short-hop RF with a module in either a gas or water meter. The module seamlessly integrates into an electromechanical or solid state meter. It returns up to three separate meter reads to a data collector in the substation using FDMA (frequency division multiple access) power line carrier technology. This enables the module to remain in constant and simultaneous communication with the data collector.

The multi-utility system is designed to work with Badger Meter’s ORION® transmitter for either gas or water. The ORION gas module mounts on the gas meter using a custom adapter plate that fits between the meter and the index. During installation, the module is programmed with the current gas meter reading, so account history is maintained. The module encodes the gas meter reading, meter identification number and tamper information. It transmits at a frequency in an unlicensed frequency band at predetermined periods, so no “wake-up” signal is required.

According to Alan Swanson, TS2 product manager at Landis+Gyr, the main advantage of deploying a fixed network multi-utility system is the continuous communication with the endpoint. Data is available on a daily basis to support off-cycle reads. Tamper and outage information is automatically collected. Customer service is improved because historical data is available to help resolve billing issues.

“A multi-functional AMI system provides more complete system coverage for a combination utility and a strong return on investment, while being simpler to administer and maintain,” Swanson said.

Command Center™, the operating software for Landis+Gyr AMI systems, processes the data for all of the meters. The software validates the data before making it available to billing, operations and engineering systems at the utility.

Along with its many command and control functions, Command Center enables the utility to access a variety of data each day, including a daily reads status report for all endpoints. Additionally, the billing day can be scheduled for any time period. For instance, Unitil’s gas day runs from 10 a.m. to 10 a.m. and Command Center can remotely program endpoints to retrieve data accordingly.

Robust communication

Unitil is a combination utility with three distinct service territories in two states. Based in Hampton, NH, it provides retail electric service to 100,000 customers, and natural gas service to 15,000 accounts in New Hampshire and Massachusetts. The utility’s Fitchburg, MA distribution center serves 27,500 electric and 15,000 gas customers across six area communities. Over half of the town’s housing stock was built prior to World War II, and predictably, many of the meters are in hard-to-read locations. As part of its system acceptance test, Unitil installed the multi-utility system in 1,000 of its most challenging locations.

According to Deschambeault, Unitil was anxious to see if the RF component of the system would work as advertised. “We’ve had different experiences with RF over the years and that part of the system was a concern for us at first. Would it do what it was supposed to do?” he said.

Ultimately, the robustness of communication between the electric and gas meters met, and in some cases, exceeded expectations. Even in the most difficult locations, only three required a repeater between the electric and gas meters.

One of these locations is a mixed-use commercial/residential building with a grocery on ground level and residential housing above. Four gas meters sit outside on the building’s main level, while the electric meters are located inside the cellar on the opposite wall. A single repeater installed in the cellar stairwell was sufficient to serve all the meters. In the majority of test locations, such as at a strip mall where a row of gas meters was located 100 feet away and behind a cement wall from the electric meters, the meters required no repeater.

Unitil contracted with Honeywell to conduct the field installation of all the AMI endpoints, and is using a second contractor to install the collection and processing equipment in substations. The utility deployed a combination of electromechanical and solid state meters..

In addition to the GE kV2c, Landis+Gyr’s multi-utility endpoint is also available in the CENTRON meter and fits most electromechanical meters. The option to choose a multi-form meter adds versatility to the multi-utility system, according to Deschambeault, especially when deploying in territories where network metering applications are common.

Unitil completed deployment of the TS2 system across all service territories in 2007. With an accelerated deployment schedule, the utility achieved full value from the system sooner, promoting a faster return on investment.

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